1. Field of the Invention
The present invention relates to an exercise therapy device such as an ergometer, and more particularly, to a control apparatus and method for an exercise therapy device capable of controlling an exercise load by using isokinetic load control and constant-watt load control in combination even when the strength of the exerciser's leg significantly differs between his/her left and right legs.
2. Description of the Related Art
Hitherto, training using an exercise therapy device such an ergometer has been carried out in an exercise therapy, which is aimed at an increase of a physical strength and rehabilitation.
As one exercise load control method for such exercise therapy device, there is known isokinetic load control capable of generating an exercise load equivalent to a muscle strength exerted by an exerciser even when the muscle strength that can be exerted by the exerciser, or the physical condition or level of fatigue of the exerciser changes with time (see, for example, Japanese Patent Application Laid-open No. 2005-192781). In such a device as an ergometer with which the exerciser carries out an exercise of operating pedals of the device, a load amount transmitted to the device differs depending on a rotational position of each pedal. In such a case, through use of the isokinetic load control, which involves smoothly adjusting the load in a process during which the rotational position of each pedal changes, the exerciser can smoothly operate the pedals.
In such isokinetic load control, when the leg strength with which the exerciser steps on the pedals differs between his/her left and right legs, the control is performed so that the load strength suited to each of the leg strengths is applied, and hence the load strength being applied differs between the left pedal and the right pedal. This control is advantageous in that even when the exercise ability of one of the left and right legs is low, an arbitrary exercise load suited to the exercise ability of each of the legs can be applied without applying an excessive load.
Meanwhile, as another exercise load control method for such exercise therapy device, constant-watt load control, in which the exercise load is controlled so that a peak value or average value of the generated load is constant, can be used (see, for example, Japanese Patent Application Laid-open No. 2001-299957).
However, the related arts have the following problem.
When the muscle strength arbitrarily exerted by the exerciser changes every time in the case where the strength of the exerciser's leg significantly differs between his/her left and right legs, the load torque applied to each pedal and the rotation speed of each pedal significantly differ between the left and right pedals. Accordingly, in particular, when the isokinetic load control and the constant-watt load control are used in combination, the load torques of the left and right pedals varies with the isokinetic load control, and hence as a result, the watt to be applied by the constant-watt load control to be described later becomes less constant, which is a problem of the related arts.